Rate of respiration and RQ

Question 1

Describe how a respirometer works.

Answer 1

It’s a chamber connected to a capillary tube with a drop of dye. As the organism in the chamber respires and uses oxygen, the pressure decreases and the liquid moves in the capillary.

Question 2

What is the control of this practical?

Answer 2

Replace the organism with an inert object of the same mass.

Question 3

How do you use the volume of oxygen consumed using a respirometer?

Answer 3

Place a fixed mass of soda lime in the respirometer with the organism. Measure the distance moved by the dye, and use the formula
Volume = distance x πr2

Question 4

How can the volume of carbon dioxide produced be found?

Answer 4

Perform two set ups, one with soda lime (A) and one without (B). Find the volume of gas used in the given time.

Volume of CO2: volume of A - volume of B

Question 5

How is the rate of respiration calculated using data from the respirometer?

Answer 5

Rate: volume of oxygen used / mass of organism / time

Question 6

State the hazard and safety precaution involved in the practical.

Answer 6

The soda lime is corrosive. Wear eye protection and gloves.

Question 7

What are the controlled variables of this practical?

Answer 7

Mass of organism
Temperature
Mass of soda lime
Apparatus might be airtight, and replace air between each set-up

Question 8

What is the formula for the respiratory quotient?

Answer 8

Volume of carbon dioxide produced / volume of oxygen absorbed